I volunteer in the chemo unit of my local hospital so I see lots of lovely quilts and blankets. In my opinion -- do not use pink & white simply because it would get dirty too fast. Patients do eat & drink while undergoing chemo and stuff gets dropped onto the blankets; plus there is the problem of fluids/blood from an IV.
Other than that, I suggest bright, cheerful colors. Make any pattern you feel comfortable with but do make it extra long. My patients recline in a reclining chair and they need to be covered from their neck down to their toes (wrap around the feet). Chemo (actually any IV) makes patients chilly so these quilts/blankets are truly used and loved.
One last suggestion, make the backing from flannel so that it won't slip off your lap easily.
Good luck and I can guarantee that whatever you make, your friend will feel your love every time she uses the quilt.